FIELD OF THE INVENTION
This invention refers to a pipe-flange coupling, via irreversible screwing at rotation.
More in particular, this invention refers to a pipe-flange coupling via irreversible screwing at rotation, particularly suited to being used in pressurized fluid circuits, subject to vibration, as for example in air compressors, or air conditioners mounted on vehicles.
In pipe-flange couplings where a leak-proof seal is required that is stable in time and can withstand vibrations at any frequency, as occurs for example in the compressor circuits of car air conditioners, the present state of the art requires that the components be welded.
This welding operation, particularly in the case of aluminium, or light alloy cast pipes, involves considerable problems in executing the weld and significant difficulties to ensure that a reliable coupling is achieved.
The most frequent drawbacks are: sagging and burrs on the seal surface; burns, or porosity in the weld caused by the use of deoxidisers; annealing of the base materials with a weakening of the structural rigidity and of the toughness of the materials themselves, etc. In addition, during operation the inevitable prolonged stress, due to the vibrations, may crack a layer of the melted material, breaking the seal.
This invention overcomes all the above mentioned drawbacks, achieving the pipe-flange coupling by screwing a fixed ring nut which maintains the pipe fixed in a corresponding hole of the flange and rotation of the pipe in the opposite sense, due to the vibrations is prevented.
According to this invention, the flange-through hole inside with the pipe is fixed includes, in the internal part opposite the fixing part, a portion with a diameter equal to the outside diameter of the pipe and in the external part, corresponding to the fixing part, a threaded portion to screw the fixing ring nut; the two internal and external portions being connected to one another by an intermediate area having a longitudinal section (along the screwing axis) which essentially has a truncated-cone shape.
The pipe has an annular projection on its surface into which the fixing ring nut engages. A ring of elastomeric material is inserted inside the pipe, beneath the annular projection and in contrast between the projection and the surface of the truncated-cone area of the hole.
In addition, the terminal part of the pipe has a cupped, or enlarged portion with an essentially cylindrical shape which inserts itself in a corresponding complementary recess made in the flange section, within and downstream of the truncated-cone seat.
Insertion of the enlarged part into a recess prevents the formation of a torsional torque exerted on the ring nut due to the vibrations which cause loosening of the threaded part.
In addition, the thrust, exerted by the split ring deformed by the pressure of the annular projection maintains the ring nut in elastic contact with an axial braking effect on the threads.
In this way a solid coupling is formed and without the possibility of rotation.
To better understand this invention, the said invention will be described in greater detail here with the help of the drawings which represent a preferred, illustrative, but non-limitative embodiment thereof.